Plate-type heat pipe

ABSTRACT

An exemplary plate-type heat pipe includes a top plate, a bowl-shaped base plate, a wick structure arranged on inner surfaces of the top and base plates and a working liquid filled therein. The base plate engages and cooperates with the base plate to defining a sealed chamber between the base plate and top plate. The working liquid is contained in the sealed chamber. The base plate defines a heat absorbing portion at a central part thereof for contacting a heat generating component. Pits are defined in the inner surface of the heat absorbing portion.

BACKGROUND

1. Technical Field

The disclosure relates to heat dissipation devices and, more particularly, to a plate-type heat pipe that has good heat dissipation efficiency.

2. Description of Related Art

Nowadays, numerous heat dissipation devices are used to dissipate heat generated by electronic devices. A heat sink with a plate-type heat pipe is a common type of heat dissipation device. A vacuum chamber is defined in the heat pipe. A wick structure is formed on an inner face of the heat pipe, and a working fluid is contained in the chamber. In use of the heat pipe, it is maintained in thermal contact with an electronic device. When the electronic device operates at high temperature, the working fluid contained in the chamber corresponding to a hotter section of the heat pipe vaporizes into vapor. The vapor then spreads to fill the chamber, and when the vapor contacts a cooler section of the chamber, it releases its latent heat and condenses. The condensate returns to the hotter section via capillary force generated by the wick structure. Thereafter, the working fluid repeatedly vaporizes and condenses to form a circulation system to thereby remove the heat generated by the electronic device.

Generally, as shown in FIG. 1, a plate-type heat pipe comprises a top plate 100, a base plate 101 engaging the top plate 100, and a wick structure 102 of uniform thickness mounted on an inner face of the top plate 100 and inner faces of the base plate 101. That is, a sealed chamber is defined between the top and base plates 100, 101, and the chamber is filled with a phase-changeable working liquid. A heat absorbing portion 103 protrudes downwardly from a center portion of the base plate 101, for contacting the electronic device. Since heat from the electronic device is conducted to the plate-type heat pipe only via the heat absorbing portion 103, the working fluid filled in the corresponding part of the wick structure 102 has to be heated and vaporized immediately; otherwise the heat would accumulate in the heat absorbing portion 103 and possibly cause damage to the heat pipe or the electronic device. However, in practice, the working liquid in the part of the wick structure that is arranged on a flat inner surface of the heat absorbing portion 103 is in poor contact with the heat absorbing portion 103, and may not be heated quickly enough to vaporize and migrate to the top plate 100.

What is needed, therefore, is a plate-type heat pipe which can overcome the limitations described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a cross-sectional view of a related art plate-type heat pipe.

FIG. 2 is a cross-sectional view of part of a plate-type heat pipe according to an embodiment of the present disclosure, the plate-type heat pipe including a heat absorbing portion.

FIG. 3 is an enlarged view of a circled portion III of FIG. 2.

FIG. 4 is a perspective view of part of the heat absorbing portion of the plate-type heat pipe of FIG. 1.

DETAILED DESCRIPTION

Referring to FIGS. 2-4, a portion of a base plate 10 and a wick structure 20 of a plate-type heat pipe according to an embodiment of the present disclosure is illustrated. Other elements of the plate-type heat pipe of the present disclosure are similar to those of the related art heat pipe of FIG. 1, and are omitted from FIGS. 2-4 of the present disclosure. Such other elements include a top plate, and a wick structure arranged on inner surfaces of parts of the plate-type heat pipe other than an inner surface of the base plate 10 as illustrated in FIG. 1.

The base plate 10 is generally bowl-shaped, and has a heat absorbing portion 12 protruding downwardly from a central part thereof. The heat absorbing portion 12 has an outer surface for contacting a heat-generating component (not shown). The heat absorbing portion 12 defines an inner recess, for receiving working liquid therein.

Particularly referring to FIGS. 3 and 4, the inner surface of the heat absorbing portion 12 to which a portion of the wick structure 20 is adhered is a cratered surface. That is, the inner surface defines a plurality of pits 120 therein. The pits 120 are evenly arranged in an array at the inner surface. For example, the array can be a regular m x n array. Each pit 120 tapers downwardly from the inner surface into the heat absorbing portion 12, and defines a polyhedral configuration. Each pit 120 has an opening with a corresponding polygon shape. In this embodiment, the pits 120 define inverted square pyramids. Openings of the pits 120 at the inner surface are square. Each pit 120 defines four inclined sidewalls that taper down deep into the heat absorbing portion 12.

In use of the plate-type heat pipe, the working liquid filled in the pits 120 is in contact with the inclined sidewalls of the pits 120. Such working liquid can be heated more quickly than other working liquid outside of the pits 120. The temperature of the working liquid filled in the pits 120 rises to vaporizing point faster than other working liquid, and is thereby vaporized firstly and quickly. The working liquid contained in the plate-type heat pipe can be vaporized in the pits 120 as soon as it has arrived back after being condensed at other areas in the chamber such as at the top plate. Thereby, the working liquid can continue to immediately transfer the heat from the heat-generating component to the top plate. Therefore, heat generated by the heat-generating component can be efficiently removed by the plate-type heat pipe. In particular, heat is not liable to accumulate at the heat absorbing portion 12, and so damage to the plate-type heat pipe or the heat-generating component can be avoided.

It is believed that the disclosure and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A plate-type heat pipe comprising: a top plate; a base plate engaged with the top plate, the base plate and the top plate cooperatively defining a sealed chamber, the base plate defining a heat absorbing portion for contacting a heat generating component, an inner surface of the heat absorbing portion having a plurality of pits defined therein; a wick structure arranged on inner surfaces of the top and base plates; and a working liquid contained in the sealed chamber.
 2. The plate-type heat pipe of claim 1, wherein each of the pits defines a shape tapering from the inner surface of the heat absorbing portion toward an opposite outer surface of the heat absorbing portion.
 3. The plate-type heat pipe of claim 2, wherein each of the pits defines a pyramidal configuration, and has a polygonal opening at the inner surface.
 4. The plate-type heat pipe of claim 3, wherein the wick structure covers the openings of the pits.
 5. The plate-type heat pipe of claim 3, wherein each of the pits has a square pyramidal configuration, and has a square opening at the inner surface.
 6. The plate-type heat pipe of claim 3, wherein each of the pits defines four inclined sidewalls.
 7. The plate-type heat pipe of claim 1, wherein the heat absorbing portion protrudes downwardly from a central part of the base plate, thereby defining a recess in the heat absorbing portion, and the inner surface is located at a bottom of the heat absorbing portion.
 8. The plate-type heat pipe of claim 1, wherein the pits are evenly arranged in an array at the inner surface of the heat absorbing portion.
 9. The plate-type heat pipe of claim 6, wherein the pits are arranged in a regular m x n array at the inner surface of the heat absorbing portion.
 10. A plate-type heat pipe comprising: a top plate; a generally bowl-shaped base plate engaged with the base plate, the top plate and the base plate cooperatively defining a sealed chamber therebetween, the base plate comprising a heat absorbing portion at a central part thereof for contacting a heat generating component; a wick structure arranged on inner surfaces of the top and base plates; and a working liquid contained in the sealed chamber; wherein a plurality of pits are defined in the inner surface of the heat absorbing portion.
 11. The plate-type heat pipe of claim 10, wherein each pit tapers from the inner surface of the heat absorbing portion toward an opposite outer surface of the heat absorbing portion.
 12. The plate-type heat pipe of claim 11, wherein each pit has a square pyramidal configuration and has a square opening at top of the inner surface of the heat absorbing portion.
 13. The plate-type heat pipe of claim 12, wherein each pit defines four inclined sidewalls tapering deep into the heat absorbing portion.
 14. The plate-type heat pipe of claim 12, wherein the wick structure covers on the opening of the each pit.
 15. The plate-type heat pipe of claim 10, wherein the heat absorbing portion protruding downwardly from a central part thereof and a recess in the inner surface thereof and a protrusion projecting downwardly from an outer surface of the base plate.
 16. The plate-type heat pipe of claim 10, wherein the pits are evenly arranged in the inner surface of the heat absorbing portion. 